Gas-producing electrochemical processes and the corresponding electrodes to be used in electrolytic appliances are known in the art; such electrodes are for instance disclosed in DE 198 16 334. The above patent describes an electrolyser for the generation of halogen gases from aqueous alkali halide solutions. As the product gas in the electrolyte negatively affects the flow behaviour in the membrane/electrode area, DE 198 16 334 suggests the installation of individual louver-type elements inclined to the horizontal plane. In this way a lateral flow is established in the cell because the gas bubbles gathering under the individual lamellar elements run upwards through the openings.
DE 198 16 334 however does not suggest how to overcome the problem that a certain amount of gas gets trapped underneath the louver-type elements, so that a considerable fraction of the membrane surface area is blinded. The fluid circulation is hindered in the blinded area, in which the gas production cannot therefore take place. Moreover, the gas stagnation diminishes the local membrane conductivity, leading to an increase in the current density in the remaining zones, which in turn leads to increased cell voltage and energy consumption.
In order to eliminate this blinding effect, EP 0 095 039 discloses lamellar elements provided with transverse recesses. In DE 44 15 146 however it is stated that said recesses are insufficient to prevent blinding. Consequently DE 44 15 146 discloses lamellar elements provided with bores or openings pointing downwards so that the gas discharge flow is enhanced.
However, this method does not solve the problem of the residual gas fraction trapped in correspondence of the contact areas and hindering the electrolyte flow.